Fries's Structure of English, language teachers have described English words as falling into two broad types: those that belong in the dictionary like 'storm' and 'confabulate', called content or lexical words, and those that belong in the grammar like 'of' and 'the', called structure, function or grammatical words.
tl;dr: Structural Words are the meaningless little words in a sentence that make it flow or move from one important word to the next.
<span>Without placing too implicit faith in the account above given, it must be agreed, that if a worthy pretext for so dangerous an experiment as setting houses on fire (especially in these days) could be assigned in favor of any culinary object, that pretext and excuse might be found in roast pig.</span>
He is too beautiful......
"On kin of cain" through to "that woful breed" Cain was the child of Adam and Eve, who killed his brother.